QlikSense User Addition

I am new to Qlik Sesene.I have set up a Qlik Sense server and for Authentication I am using Active Directory method. I have created active directory and executed the sync task. After that I can see that Directory listed. Now I want to add user in Login access users to provide access but I am not able to Lookup /search the user that are listed in AD which is created. Is there anything I am missing or dong wrong in order to add the user to provide access?. Can anyone help me on to this?